Refrigeration apparatus



Sept. 6, 1966 w. E. CLARK REFRIGERATION APPARATUS 2 Sheets-Sheet 1 Filed May 20, 1963 FIG. I

FIG. 2

INVENTOR. WILLIAM E. CLARK.

ATTORNEY.

W. E. CLARK REFRIGERATION APPARATUS sept. 6, 1966 2 Sheets-Sheet 2 Filed May 20. 196s INVENTOR.

WILLIAM E. CLARK.

ATTORNEY.

United States Patent O 3,270,517 REFRIGERATION APPARATUS William E. Clark, Syracuse, N.Y., assignor to Carrier Corporation, Syracuse, N.Y., a corporation of Delaare Filed May 20, 1963, Ser. No. 281,400 9 Claims. (Cl. 62-115) This invention relates broadly to refrigeration apparatus. More particularly, this invention relates to an improved heat transfer unit, together with its mode of operation, of the kind employed with mechanical refrigeration systems.

In refrigeration machines having a capacity in excess of 100 tons, it is important that the equipment be fabricated from parts Iof relatively light weight and in a manner permitting ease of handling. In order to obtain e-conomies involved in equipment of the kind under consideration, it is important that the heat transfer functions in a mechanical refrigeration machine be achieved with a unit that is as light and compact as possible. At the same time, it is desirous that the equipment be fabricated in such a manner that operating economies such as improved performance and greater capacity for a given size be realized.

It is accordingly the chief object of this invention to provide an improved heat transfer unit for a mechanical refrigeration machine which permits the condensing and evaporating action to tbe accomplished in a single structure so that the overall size and weight of a given machine may be reduced.

A further object of the invention is the provision of an improved method of supplying liquid refrigerant to an evaporator of a machine of the kind under consideration having a plurality of tubes forming a tube bundle for accommodating medium to be cooled. Evaporators of the type to which this invention pertains are commonly called flooded evaporators and a given machine is designed so that all of the tubes are wetted by liquid refrigerant within a tube bundle in the evaporator under normal operating conditions.

An additional feature of the invention is the provision of an improved arrangement for assuring better performance of a refrigeration machine under low load conditions. The phrase, low load, as applied here, means operation under circumstances where the refrigeration demand is 'below that for which the machine is designed.

A still further object of the invention is the provision of an improved heat transfer structure including a single shell having ran arcuate partition dividing the interior of the shell into a condenser compartment and an evaporator compartment. With such a construction, it will be obvious that `substantial pressure differences within the shell occur during normal operation of the machine. This invention provides a unique structural arrange-ment of the tube support parts enabling the tube support members to participate in resisting the stresses within the shell that occur as a result of the pressure differences involved.

Another object of the invention is the provision of a unique arrangement for handling noncondensibles from the condenser compartment of the heat transfer unit. Communication between the condenser compartment and a noncondensible collecting chamber permits the noncondensibles to accumulate at the top of the condenser compartment and flow into the chamber. Supported within the chamber is a conduit forming a part of the condenser cooling circuit. The conduit is supported in a portion of the tube sheet, serving the condenser compartment, having a projection into the purge chamber.

A further object of the invention is the provision of a novel arrangement for supplying the liquid refrigerant to the tube bundle employed in the evaporator. To this ice end, there is provided a flat plate member extending along the bottom of the evaporator compartment and supported so as to create a space beneath the plate. An opening in that portion of the shell beneath the plate connects with a passageway leading to conventional refrigerant flow control assembly employed for the purpose of passing condenser liquid to the evaporator. Ove-rlying the plate member described above is a perforated plate formed so as to be in spaced relation to the top of the plate and a flow diverting support member. Liquid refrigerant owing to the evaporator flows upwardly through the plate :and the perforated member so as to submerge a predetermined number yof rows of tubes in the tube bundle.

These and other objects of the invention will be apparent u-pon a consideration of the ensuing specification and drawings in which:

FIGURE 1 is a perspective view of a machine constructed in accordan-ce with this invention;

FIGURE 2 is a view in section taken along lines II-II of FIGURE l illustrating certain parts of the machine;

FIGURE 3 is a view similar to that illustrated in FIG- URE l wherein certain parts of the machine are broken away in the interests of clarity; and

FIGURE 4 is a partial view of the refrigerant distribution :assembly serving the evaporator.

Referring more particularly to the drawings for an illustration of a machine incorporating lthe teachings `of this invention, there is shown -a centrifugal refrigeration machine 1li incorporating a centrifugal compressor 12 for the purpose of extracting gaseous refrigerant from the evaporator and forwarding it under increased pressure to lthe condenser.

A particular feature of this invention is the construction of the heat transfer unit associated with the refrigeration machine. Normally, it is conventional that two separate heat transfer units be provided to accomplish the normal condensing and evaporating functions in the ma- -chine of the type under consideration. This invention involves the provision of `a cylindrical shell member 14 in which there is provided an arcuate partition 16 dividing the interior of the shell into a condensing compartment 18 and an evaporator compartment 20.

The condensing chamber, it will be understood, is under substantial pressure determined by the discharge pressure of the compressor employed. The evaporator compartment however, is under reduced pressure being in communication with the suction of the compressor. Under these circumstances, it will be appreciated that partition `16 will be under a substantial stress acting in a direction to cause disengagement of the partition from the interior walls of the shell. In order to prevent this, there are provided tube support sheets Z2 of a particular configuration in the condenser compartment. The tube sheets are Welded to the partition and are provided with ears 21, 2.1' arranged to project through openings 23 provided in the shell. The ear or projection 21 is welded to the shell as it projects through opening 23. Once the projection 21 has been secured to the shell, the portion projecting beyond the outer surface of the shell is removed. The projection 21 is also welded to the shell and is enclosed by wall members 24 so as to define a chamber 26 in communication with openings 28 and 3l) formed in the cylindrical shell.

Referring to the evaporator chamber 20 there is provided a number of tubular members 29 forming a tube bundle supported in conventional tube sheets. It will be appreciated that the ends of the cylindrical shell are provided With conventional water boxes 27 for the purpose of directing water through t-ubular members 29. Tubular members 19 are also supported in the tube sheets 22 disposed within the condenser compartment 18. The purpose of the tubular members 19 is to provide a plurality of passages for the flow of cooling medium through the condenser compartment.

It will be noted that there is provided an opening 31 in the partition separating the condenser compartment from the evaporator compartment. Opening 31 permits condensate rformed in the condenser chamber to drain to a chamber 33 housing a float valve assembly 34 for regulating flow of liquid refrigerant to the evaporator chamber 20. In communication with the chamber 33 there is provided a passageway 35 formed by arcuate wall 36 and the outer surface of the cylindrical shell. The end of the passageway remote from chamber 33 connects with an opening 15 formed in the bottom of the shell 14. Liquid refrigerant flowing in passageway 35 collects in space 32 formed beneath plate 37 supported as shown in FIGURE 2 on the inner surface of the cylindrical shell. Plate 37 is substantially coextensive with the length of the tube bundle located in the evaporator compartment 20. Openings 37 are spaced along the center line of plate 37 permitting liquid refrigerant to escape from the space 32 located beneath the plate. Overlying plate 37 is a second plate 38 provided with perforations 38 throughout its length and width. Plate 38 is provided with legs 39 arranged so as to define a chamber 40 between the two plate members 37 and 38. A structural support member 41 is interposed between the two plates overlying the openings 37 formed in plate 37. Support 41 has a series of spaced legs 42 so that refrigerant owing upwardly through plate 37 ows transversely through the openings between the legs 42 into the chamber 40. From the chamber 40 the liquid refrigerant flows through the perforations 38 upwardly over the tubular members 29 forming the tube bundle in the evaporator 20..

The purpose of plate 37 in the refrigerant distributlon system is to assure even distribution of the refrlge'rant throughout the length of the bundle. The relatively high velocity refrigerant flow enters openings 37' and 1s prevented from further upward flow by support plate 41. It will rbe obvious that transverse flow of the refrigerant occurs through the openings between legs 42. IIow the refrigerant sprays upwardly through the perforations 3 8 in plate 38 with sufficient velocity to wet all the tubes '1n the tube bundle. f The agitation created by the velocity imparted to the refrigerant during liow through opening 37 and 38 causes improved heat transfer performed 1n the tube bundle. The -assembly including plates 37 and 38, together with support member 41, prevents local concentration of refrigerant flow to the tube bundle. With this construction the liquid refrigerant is introduced over the tube surface with sufficient velocity to reach the uppermost row of tubes in the tube bundle as well as the rows below the uppermost row. Thus the heat transfer performance of the tube bundle is greatly improved over that encountered when the tube bundle or the major portion thereof is submerged by liquid refrigerant. Use of the construction described will permit a reduction in the refrigerant charge for the machine. In other words, the heat transfer available with the arrangement described is superior to that obtained with submerged or partially submerged tube bundles.

In addition to the opening 15 enabling liquid refrigerant to be supplied to the evaporatorcompartment, there is an opening 43 providing communication between space 32 and the high pressure side of the compressor. Conduit 44 is provided for the purpose of supplying high pressure refrigerant to the evaporator compartment under circumstances where a predetermined low load condition indicates that additional refrigerant in the evaporator is desirable. For example, in orde1 to sustain the action created by the refrigerant distribution assembly as described above, it may be necessary to compensate for the reduced agitation accompanying the lower refrigerant flow occasioned by low load. With the construction shown, high pressure gaseous refrigerant is supplied to the bottom of the evaporator to the distribution system formed by plates 37 and 38. Under these circumstances, once communication is established by opening valve 46, located in conduit 44, the supply of liquid refrigerant continues in the manner described. This results in the utilization of a greater proportion of the tube bundle for heat transfer action than normally occurs at low load condition when the liquid level of refrigerant is depressed below that existing at normal load operation in conventional equipment.

Considering the operation of the invention, compressor 12 is operated so as to create a predetermined pressure in the evaporator compartment 20 of the shell through conduit 48 connecting with the evaporator and the suction of the compressor. Liquid refrigerant present in the evaporator evaporates as it extracts heat from cooling tluid owing through the tubular members 29 forming the tube bundle in the evaporator compartment 2t).

The vaporized refrigerant is compressed and forwarded through discharge line 50 to the condenser compartment 18 where it is liquefied as heat is extracted therefrom by the cooling medium flowing through the tube bundle located in the condenser. Noncondensible gases in the condenser collect .at the top of compartment 18 and ow through opening 28 into noncondensible collecting chamber 26 where they are liquefied at least in part by the action of pipe 25 vforming a part of the condenser cooling circuit. The liquid refrigerant formed in the chamber 26 flows through opening 30 into the condenser compartment and joins the condensate flowing through screen 33 to the chamber 33 h-ousing the float valve assembly 34.

It will be noted from FIGURE 2 that a baille 52 is provided opposite the portion of the tube bundle in direct alignment with the end of conduit 50 providing flow of gaseous refrigerant to the condenser. Batlle 52 is supported by struts 54 in the con-denser chamber.

Liquid refrigerant is delivered to the evaporator compartment through the action of float Valve assembly 34 permitting flow through the 4passageway 35 leading to the space 32 beneath the plate 37. As heat is extracted from the medium flowing 4in the tube bundle in the evapotrator, 4gaseous refrigerant is formed completing the refrigeration cycle. With the construction shown, .at least a part of the vapor formed in the evaporator contacts the underside of .partition 16, sub-cooling the liquid owing over the upper side of the partition.

Under low load condition, valve 46 is actuated to open position enabling iiow throughr conduit 44 to occur. Valve 46 may be controlled by any combination of system `characteristics evidencing a low load condition. For illustration, valve 46 may respond to a predetermined increase in superheat in the vapor leaving the tube bundle. It will be appreciated that at reduced loads refrigerant ow drops so that the uppermost tubes are not wetted causing .an increase in s-uperheat in the refrigerant vapor. When the desired agitation action is re-established by the flow of refrigerant from line 44 the superheat is reduced because the upper tubes are now wetted.

A feature .of the invention described above is the construction of the Various parts forming the cylindrical shell. With the arrangement shown, the tubular support members 22 in the condenser compartment are placed under tension as 'a result of the stresses created in the partition and portion of the shell subject to high pressure refrigerant. Should liquid refrigerant be carried upwardly against the partition, it w-ill be vaporized as it contacts the relatively warm partition. Another feature of the construction described is the lack of a need for eliminators in the gas stream flowing to the compressor. The gas leaving the tube bundle is of a relatively low velocity because of the overall width of the shell. Thus `any tendency for entrainment of droplets of liquid refrigerant is obviated.

While I have described a preferred embodiment of the invention, it will be understood the invention is not limited thereto since it may be otherwise embodied within the scope `of the following claims.

I claim:

1. A refrigeration machine including a refrigerant compressor; heat transfer means comprising a shell member of a substantially cylindrical configuration, partition means dividing the shell member into a condenser compartment and an evaporator compartment, means forming a restricted refrigerant flow passage from the condenser compartment to the evaporator compartment; a plurality of tubular members forming a circuit for the iiow of cooling medium disposed in said condenser compartment, a plurality of upright plate members supporting said tubular members; means forming a chamber having communication with said condenser compartment; sa-id tubular member support plates being provided with Va portion projecting into said chamber; means forming a section of said -circuit for condenser cooling medium, supported in saidy projecting portion to liquefy condensible gases flowing into said chamber; means forming .a connection between said compressor discharge and said condenser compartment; and means forming -a connection between said compressor suction and said evaporator compartment.

2. A refrigeration machine including a refrigerant compressor, heat transfer means comprising a shell member of a substantially cylindrical configuration, partition means dividing the shell member into a condenser comp-artment and an evaporator compartment, means forming a restricted refrigerant flow passage from the condenser compartment to the evaporator compartment, a plurality of tubular members forming a circuit for the flow of cooling medium disposed in said condenser cornpartment, a plurality of upright plate members supporting said tubular members, means forming a chamber having communication With said condenser compartment, means forming a section -of said circuit for condenser cooling medium for liquefying condensible gases flowing into said chamber, means forming a connection between said compressor discharge and said condenser compartment, and means forming a connection between said compressor suction and said evaporator compartment.

3. In a refrigeration machine including ya compressor, a condenser, refrigerant flow control means, and an evaporator wherein said evaporator comprises a shell having van opening therein .and .a plurality of tubular members arranged within said shell to form a tube bundle, means for supplying refrigerant from the refrigerant flow control means to the evaporator, said means including a wall forming, with a portion vof the outer surfaceI of the shell, a passageway for conducting refrigerant from the refrigerant flow control means to the shell opening, a first plate, having a plurality of spaced openings extending along its central axis, supported on the inner surface of the shell beneath said tube bundle overlying said shell opening, a perforated plate coextensive with said first plate and a flow diverting support interposed between said plates for maintaining same in spaced relation, and acting as a target baffle to prevent direct irnpingement of high velocity liquid on the tubes.

4. The invention set forth in claim 3 including a line connecting the lspace beneath said tube bundle with the high pressure side of the refrigeration machine.

5. `In a refrigeration machine including a compressor, a condenser, refrigerant ow control means, and an evaporator wherein said evaporator comprises la shell having an opening therein and a plurality of tubular members arranged within said shell to form a tube bundle, means for supplying refrigerant from the refrigerant flow control means to the evaporator, a first plate, having a plurality of spaced openings supported on the inner surface of the shell beneath said tube bundle overlying said shell opening, a perforated plate coextensive with said first plate and a support having a plurality of spaced lateral openings interposed between said plates for maintaining same in spaced relation.

6. The method lof supplying refrigerant to an evaporator having a tube bundle assembled therein and including `a compressor, a condenser and a refrigerant control means connected with said evaporator to form a closed circuit for the liow of refrigerant which comprises the steps of presenting relatively low pressure liquid refrigerant to an axial lcollection space beneath the tube bundle and directing refrigerant upwardly and outwardly from the space at a plurality of spaced locations to a chamber provided with a perforated cover so that liquid refrigerant flow continues upwardly over the tube bundle in a substantially uniform flow pattern.

7. The method set forth in claim 6 including the step of introducing gaseous refrigerant flowing from the compressor substantially centrally of the axial collection space beneath said tube bundle.

3. The method set forth in claim 7 wherein the step of introducing gaseous refrigerant is initiated in response to a ypredetermined variation in an operating condition within the machine.

9. The method of operating a refrigeration machine including a compressor, a condenser, an evaporator an-d yrefrigerant flow means connected to form a circuit for the ow of refrigerant which comprises the steps of:

(a) discharging gaseous refrigerant into a portion of a substantially cylindrical shell having a partition defining a high pressure compartment and a low pressure compartment;

(b) liquefying the discharged gaseous refrigerant with cooling medium flowing through said high pressure compartment;

(c) collecting the liquefied refrigerant and directing it to the low pressure compartment;

(d) directing the liquefied refrigerant over tubular members in said evaporator to cool medium iiowing Within said tubular members whereby said liquid refrigerant is evaporated;

(e) extracting the evaporated refrigerant from the shell through a path such that at least part of the flow of evaporated refrigerant contacts the .partition defining the compartments to reduce the velocity of the evaporated refrigerant and discourage entrainment of liquid refrigerant therein.

References Cited by the Examiner UNITED STATES PATENTS 1,575,818 3/1926 Carrier 62-115 1,743,989 1/1930 Wainwright 165-174 2,247,107 6/ 1941 Waterfill 62-504 X 2,312,312 3/ 1943 Be'line 62-504 X 2,324,627 7/ 1943 Jones 62-475 X 2,713,895 7/1955 Eckstrom 239-504 X 2,791,105 5/ 1957 Aronson 62-504 X 3,070,974 1/1963 Greenwald 62-197 FOREIGN PATENTS 577,447 5/ 1933 Germany.

361,816 11/1931 Great Britain.

381,412 10/ 1932 Great Britain.

LLOYD L. KING, Primary Examiner. ROBERT A. OLEARY, Examiner. 

6. THE METHOD OF SUPPLYING REFRIGERANT TO AN EVAPORATOR HAVING A TUBE BUNDLE ASSEMBLED THEREIN AND INCLUDING A COMPRESSOR, A CONDENSER AND A REFRIGERANT CONTROL MEANS CONNECTED WITH SAID EVAPORATOR TO FORM A CLOSED CIRCUIT FOR THE FLOW OF REFRIGERANT WHICH COMPRISES THE STEPS OF PRESENTING RELATIVELY LOW PRESSURE LIQUID REFRIGERANT TO AN AXIAL COLLECTION SPACE BENEATH THE TUBE BUNDLE AND DIRECTING REFRIGERANT UPWARDLY AND OUTWARDLY FROM THE SPACE AT A PLURALITY OF SPACED LOCATIONS TO A CHAMBER PROVIDED WITH A PERFORATED COVER SO THAT LIQUID REFRIGERANT FLOW CONTINUES UPWARDLY OVER THE TUBE BUNDLE IN A SUBSTANTIALLY UNIFORM FLOW PATTERN. 